Mother's Bioshelter Greenhouse
(Page 3 of 4)
July/August 1986
By the Mother Earth News editors
Should you earth berm? Banking the walls of a building with earth is a good way to minimize heat loss . . . if the site lends itself to such a technique. We happen to have quite suitable slope and soil for earth sheltering, but we wouldn't recommend it if you're building on flat ground or in expansive clay. Instead, you might want to build with minimally reinforced concrete block (or simply frame the entire structure) above ground and increase the insulation level. There's also a good chance that this approach would prove to be less expensive.
RELATED CONTENT
In May of 2007, a tornado struck Greensburg, Kan., destroying most of the town. Since that time, Gr...
The 2008 winner of the People’s Choice for Green Business of the Year has been announced! Find out ...
Opt for green energy by choosing to purchase green power from your local utility company....
The Healthy Building Network’s Pharos Project aims to tap the collective knowledge of green buildin...
When you start reading about technology, it seems as though every day there’s a revolutionary new b...
Masonry insulation: Use extruded polystyrene foam, and add an extra inch if you experience more than 4,500 heating degree-days in your locale. Use either wire lath and stucco or a resilient stucco such as PennKote to protect the exposed insulation from sunlight.
Waterproofing: We don't consider small amounts of seepage to be a particular problem in a greenhouse, so the below-grade walls are really more water- resistant than waterproof.
Floors: We used a 6" layer of gravel for our floor. A properly sloped concrete floor with appropriate drains would be nice . . . but expensive.
Pressure-treated lumber: Pressure-treated lumber has been specified in all areas that are likely to be moist. There are recognized hazards to the use of such lumber, but the only alternatives are very expensive: cypress, redwood, or some other rot-resistant wood. Believe us, standard spruce-fir boards will deteriorate quickly inside a humid greenhouse.
Glazing: Our roof glazing is recycled 3/8" X 4' X 8'8" tempered glass that had been used to manufacture plexiglass. This isn't a standard store-bought size, so if you're unable to find recycled material, you may have to have glass cut to size or alter the rafter spacing to suit a different size pane. Other glazing in the building may be tempered or not, depending on your concern and your pocketbook. (Tempered glass would certainly be safer, but it's more expensive than single-strength because it must be customcut to the odd shapes and then tempered.)
Roofglazing strips: To secure and seal the roof glazing, we set the sheets about 3/4" apart in beds of silicone caulk, added another layer of sealant on top, pulled pressuretreated 2 X 4s down on the glass with screws through the gaps, and covered the wood with aluminum flashing.
Drainage: Water-shedding details, such as the bevel on the windowsills, are quite important for preventing rot, even if pressuretreated lumber is used. In fact, we facenailed a drip edge all the way around the exposed part of the building at the sill level. This was made by ripping 2 X 4s in half on a 30° bevel. The strip not only allows water to run off the walls but also serves as the upper stop for the rigid insulation attached to the masonry below.
